Crystal design of bismuth oxyiodide with highly exposed (110) facets on curved carbon nitride for the photocatalytic degradation of pollutants in wastewater

Abstract

Crystalline materials with specific facet atomic arrangements and crystal facet structures exhibit unique functions according to their facet effects, quantum size effects and physical and chemical properties. In this study, a novel high-exposure (110) facet of bismuth oxyiodide (BiOI) was prepared (denoted as BiOI-110), and designed as nanosheets rich in oxygen vacancies by crystal facet design and regulation. Graphitic carbon nitride was designed as curved carbon nitride with dibromopyrazine, denoted as DCN, which contributed to a significant structural distortion in plane symmetry and improved the separation of charge carriers. Novel heterostructured BiOI-110/DCN nanosheets with a high-exposure (110) facet and abundant oxygen vacancies were successfully designed to enhance the photocatalytic degradation of organic pollutants. It was demonstrated that complete and tight contact between BiOI-110 and DCN was achieved by changing the size and crystal facet of BiOI. Oxytetracycline (OTC) and methyl blue dyes were used as targets for pollutant degradation, and 85.6% and 96.5% photocatalytic degradation efficiencies, respectively, were observed in the optimal proportion of 7% BiOI-110/DCN. The experimental results and electron spin resonance analysis showed that •O2− and h+ played a major role in the process of pollutant degradation. Additionally, high-resolution liquid chromatography-mass spectrography was used to identify the reaction intermediates of OTC, and the possible degradation pathway of this pollutant was proposed. Finally, the excellent reusability of BiOI-110/DCN nanomaterials was confirmed, providing a new approach for the removal of antibiotics that are difficult to biodegrade. Overall, crystal facet design has been proven to have broad prospects in improving the water environment. [Figure not available: see fulltext.].